Method of forming uranium carbon alloys



Patented Oct. 24, 1950 METHOD OF FORMING URANIUM CARBON ALLOYS James H. Carter, Harrisonburg, Va., and Adrian.

H. Daane, Ames, Iowa, assignors to the United States of America as represented by the United States Atomic Energy Commission No Drawing. Application August-12,1944,

Serial No. 549,282

2 Claims. (01. 7522) This invention relates to uranium-carbon compounds and more particularly to uranium-carbon alloys having a low carbon content. More specifically, our invention is concerned with the formation of uranium carbides and uraniumcarbon alloys from uranium metal and carbon.

It is an object of this invention to provide a process for the preparation of uranium-carbon compounds and alloys.

Another object of this invention is to provide gressively smaller for each given temperature a process for the production of uranium-carbon increment. The desired temperature is m ain compounds and alloys of low carbon content from tained for a period of from 20 to 60 minutes. uranium and carbon. At the end of this time the reaction has taken A further object of this invention is to provide placebetween the uranium and carbon and an i a process for the production of uranium-carbon alloy or compound has been formed. The duracompounds and alloys having a selected low tion of heating may be such thatthe increasing carbon content. carbon content of the uranium-carbon alloyypro- Other objects and advantages of this invention duces an alloy that solidifies at the specific temwill be readily apparent from the following deperature maintained; Uranium-carbon com-. scription of preferred embodiments of our inpounds up to at least 9 per cent carbon content vention. and probably with higher carbon content can be Broadly stated, it has been found that uranium produced by this method. v I 3; l and carbon may be heated in contact with each The increase of carbonpercentage obtained in other at a temperature in excess of the melting the uranium-carbon-alloy by the variation in the point of uranium for a sufficient time to form temperature at which the graphite crucible and adesired uranium-carbon compound or alloy. melt are maintained is shown by the data in It has been found that there are two ways of .the following table: preparing uranium-compounds or alloys in ac- Table cordance with the method of our invention. One method includes melting uranium metal and M t P G placing the molten metal in contact with a carbon 3 5333 er surface at a temperature in excess of the melting ture p Weight point of uranium. Carbon is dissolved from the carbon surface by the molten metal, forming a Mi'lwtes 1,375 40 0.137 uranium-carbon compound or alloy, and the 5 1,400 20 168 product obtained upon cooling the solution is substantially homogeneous. Following this meth- 11 30 0:775 0d, the uranium is melted and the molten metal is transferred to a carbon crucible, and thereafter the temperature of the crucible and the melt 40 is maintained at the desired temperature for a Another mode of preparing uranium-carbon selected period of time. The amount of carbon compounds or alloys consists in mixing powdered dissolved from the carbon surface and, thereuranium metal with powdered carbon and then fore, the composition of the uranium-carbon pressing the mixture into small blocks under high compound or alloy depend primarily upon the pressure, 20-50 tons p. s. i., for example, and temperature at which the crucible and melt are then heating the pressed blocks in a temperature maintained, and also upon the ratio of carbon range above the melting point of uranium and surface to the mass of the molten uranium. The below the melting point of the alloy produced, composition likewise depends upon the duration preferabl between 1800 and 2000 C. The operof heating and upon the mixing or stirring efationmay'b carried on in agraphiteor aberyllia fected. The uranium-carbon compound formed crucible. When the process takes place in a' has a low solubility in the molten uranium metal graphite crucible, the pressed block is supported and during the operation of making the uraniumon a false bottom of uranium sesquicarbide, carbon alloy a carbide crust is formed next to the UzCs, to prevent the absorption of carbon from V crucible. Therefore, if the carbon content of the uranium-carbon alloy produced is to be increased, progressively higher temperatures and stirring during the period of dissolving are required, to attain this higher carbon percentage; At low the graphite crucible. The heating of the pressed block causes the uranium carbon alloy to become more compact. The extent to which this sintering or shrinking takes place depends upon the temperature and the period of heating, as the degree of sintering is increased by higher temperatures and longer heating periods. Therefore, the density of the uranium carbon alloy produced is determined among other things by the temperature at which heating is carried on and the length of the period of heating. The temperature is maintained in a range of from 1800 to 2000 C. depending upon the carbon percentage desired in the alloy form. The higher the carbon content the higher the reaction temperature should be maintained. The material is preferably maintained in an atmosphere of carbon dioxide up to the point of the heating of the pressed blocks. The heating is preferably carried on in a vacuum and the temperature during the operation is raised gradually and maintained at the desired maximum for about 10 to 15 minutes.

an example of the mode of preparing uranium-carbon allo by the use of pressing and heating carbon and uranium, the mixture consisted of 78.8 grams of powdered uranium and 3 grams of powdered carbon pressed at 20 tons, giving a block inch x inch x 2 inches. This block was heated in a zirconia crucible in a vacuum at between 1800 and 2000 C. An analysis of the sample obtained from this process showed a composition of 95.7 per cent uranium by weight and 3.6 per cent carbon, the remaining .7 per cent being unreacted uranium.

It' wi1l be apparent to those skilled in the art that various modifications may be made without 5.

1. The process for forming uranium-carbon alloys consisting of mixing substantially theoretical amounts of powdered uranium and powdered carbon with regard to the final content desired, pressing said mixture and sintering said pressed mixture at a temperature between 1800 C. and 2000 C. in vacuum, whereby said resultant alloy is maintained in the solid state.

2. A process of forming uranium-carbon alloys consisting of mixing uranium powder and carbon powder in the quantities desired in said alloy, compressing the mixture thus produced while maintaining it in an atmosphere of carbon dioxide, and heating said compressed product to a temperature ranging from 1800 to 2000 0., whereby said resultant alloy is maintained in the solid state.

JAMES H. CARTER. ADRIAN I-I. DAANE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,829,950 Voigtlander Nov. 3, 1931 1,876,175 Stoody Sept. 6, 1932 2,113,171 Cooper Apr. 5, 1938 OTHER REFERENCES 

1. THE PROCESS FOR FORMING URANIUM-CARBON ALLOYS CONSISTING OF MIXING SUBSTANTIALLY THEORETICAL AMOUNTS OF POWDERED URANIUM AND POWDERED CARBON WITH REGARD TO THE FINAL CONTENT DESIRED, PRESSING SAID MIXTURE AND SINTERING SAID PRESSED MIXTURE AT A TEMPERATURE BETWEEN 1800* C. AND 2000*C. IN VACUUM, WHEREBY SAID RESULTANT ALLOY IS MAINTAINED IN THE SOLID STATE. 